As known in the art, door facings also known as “door skins” may be secured to a support structure or frame to form a hollow core door. Such facings may be molded from a polymeric material, such as sheet molding compound (“SMC”). SMC may be molded to form a door facing including one or more depressions or grooves, such as one or more square or rectangular depressions. These depressions may define the perimeter of one or more simulated panels. Alternatively, the facings may be flush.
The door facings are secured to opposing sides of the frame, forming hollow spaces between the facings. A core component or material is sometimes used to fill the hollow spaces. Conventional core materials for use in hollow core doors include corrugated cardboard, paper, foam, or fiberboard.
It is sometimes desirable to provide an exterior door that can withstand impacts from flying debris, such as in a high velocity wind zones. Doors are sometimes required to pass certain performance tests, such as those developed by the American Society of Testing Materials (ASTM) which test the performance of doors exposed to the effects of windstorms and impact testing. Doors may also be required to meet regional performance tests within a particular state, such as Florida. The Florida Building Code sets out stringent requirements for building components so that buildings can withstand hurricanes and other severe weather conditions. Impact testing for wind-borne debris is performed on exterior doors and other building components. Sections 1625 and 1626 of the Code provide the specifications for the impact testing. For “large missile” impact tests, a 9 pound two-by-four is projected at the surface of the test specimen at a speed of about 50 feet per second (34.1 miles per hour) using a compressed air cannon. The large missile test is used on building components that will be located less than 30 feet above the ground. In this test, each specimen receives two impacts, one in the center and one in a corner of the specimen. Once the large missile testing is completed, a fatigue load testing is performed on the specimen.
During the fatigue load testing, a cyclic large predetermined pressure load is applied to the test specimen to ensure that the specimen does not detach from its respective mounting. The pressure is applied by a compressed air supply blower during forward test loading periods and reverse test loading periods in which a pressure differential based on a wind velocity of 75 miles per hour is formed across the entry door or building component in a testing chamber. Permanent deformation and the maximum deflection are recorded for each specimen. An exterior door or other building component “passes” these tests if three specimens reject the two missile impacts without penetration and resist the cyclic pressure loading with no crack forming that is longer than 5 inches and wider than 1/16 of an inch.
The “small missile” impact test includes projecting 30 small steel balls of about half a pound and 5/16 of an inch in diameter at the exterior building component at different locations at a speed of 130 feet per second (88.6 miles per hour). The “small missile” impact test is performed on building components that will be located more than 30 feet above the ground. Once the small missile impact test is completed, the fatigue load testing is performed by applying the cyclic pressure to determine whether the specimen will detach from its mountings. Permanent deformation and the maximum deflection are recorded for each specimen. An exterior door or other building component “passes” these tests if three specimens reject the small missile impacts without penetration and resist the cyclic pressure loading with no crack forming that is longer than 5 inches and wider than 1/16 of an inch.
Testing Application Standards (TAS) sections 201-94, 202-94, and 301-94 provide the protocols for the large missile, small missile, and fatigue loading impact tests.
Various attempts have been made to provide a hollow core door that can withstand impact testing. One design provides a hollow core door having a mat disposed within the door cavity and between the opposing door facings. A cementitious material is poured around the mat. Such doors are relatively expensive and difficult to assemble. In addition, they are relatively heavy, and therefore difficult to store, transport and install. Other designs provide for metal door facings. Such doors are also relatively expensive. In addition, they are often less desirable to consumers because they lack aesthetic detail, and may rust and dent.
Conventional impact resistant doors are typically made impact resistant during the manufacturing processes used to fabricate the door skins themselves. Thus, these doors are manufactured specifically to be impact resistant and are then placed on the market. However, consumers have little choice in the variety of doors that can be made high impact resistant. That is, consumers typically have a limited number of options for selecting from among styles and sizes of hollow core doors that are made impact resistant.
Additionally, the manufacture of impact resistant hollow core doors typically requires a substantial amount of equipment and capital, thus making impact resistant doors relatively expensive to manufacture.
Therefore, there is a need for an impact resistant door that overcomes some or all of the above noted problems and disadvantages.